DCC head-scratcher

[jagged ben]

Another possibility might be that you accidentally 'nested' universal consists.  That is, if you MU'd the top engine of one consist to another consist, then both will respond to the second consist address.  Depending on the directions when you did this they may run in the same direction or opposite directions. 

[peteski]

Another possibility might be that you accidentally 'nested' universal consists.  That is, if you MU'd the top engine of one consist to another consist, then both will respond to the second consist address.  Depending on the directions when you did this they may run in the same direction or opposite directions. 

That scenario seems more likely as the problem as stated is "... everything works fine for some indeterminate time (weeks or months), and then all of a sudden (for example) consist A will suddenly start responding as if it's consist B. Consist A will still respond to the consist A address, but it will also mirror commands sent to consist B."

I don't think any Digitrax throttle can simultaneously send commands to 2 separate loco addresses (whether those addresses would be for individual locos or universal consist addresses).

[MK]

Since I'm not the OP, I'll defer your question and comments to him. 

[MVW]

Thanks all for the help. I'm replying to several comments here.

This definitely isn't an issue of inadvertently "nesting" addresses. Things will be fine with every consist playing nicely for an extended period ... and then they aren't.

Also, this isn't an issue tied to failure to press "Select" on the UT4. I've had this happen to me when I'm the only one running trains, and I'm only using the command station.

At this point, I'm probably going to reset the command station, and may also follow Peteski and Gary Hinshaw's lead of using advanced consisting.

I appreciate the assistance! And I'll report back.

Jim

[John]

Thanks all for the help. I'm replying to several comments here.

At this point, I'm probably going to reset the command station, and may also follow Peteski and Gary Hinshaw's lead of using advanced consisting.

Jim

Reset is a good idea ..

[Maletrain]

With Digitrax, it is possible for more than one throttle to control the same address.  That usually happens when you do not properly "dispatch" the address from one throttle and then "steal" it with another throttle.

Before resetting everything, you might want to try acquiring the addresses with each throttle and making sure that you properly dispatch them from each.  Then check to see if the problem still persists.

To properly dispatch an address, make sure that the speed is set to zero and the toggle switch is in "brake" (middle) position.  If a "slot" is showing a speed step other than zero, the address will (usually) not properly be released in the command station "slots".

You also need to realize that the way "Universal" consisting works with Digitrax is that it has the command station associate the slot for the non-lead loco with the slot for the lead loco, and then it knows to send the same command to both addresses when a throttle tells it to send a command to the lead loco address.

I am not that familiar with a DCS50.  But, if it only can accommodate 10 slots, then that is 10 loco addresses, which would potentially be only five pairs of consisted locos, before hitting "slot max" where all of the slots are full, and no other addresses can be added.  It is not unlikely that one slot is taken by "00", because of a UT4 being plugged in before setting its address at some point.  And, 2 throttles both able to control the same address will take 2 slots.

I did not look up what the error message is for the slots being full on a DCS50, but if you have the manual for that, check and see if you are having whatever the symptoms are.

Good luck.  Tell us what happens.

And, it you don't find the solution soon, try asking on the Digitrax group in groups.io  https://groups.io/g/Digitrax-Users

[MVW]

Again, this is definitely not an issue of two throttles controlling the same address.

Two nights ago, this occurred when I was operating by myself, and not even using the UT4. I operated three different consists using only the command station throttle. All behaved as they should, for probably a couple hours. Then I went to acquire one of the same three consists, and it behaved as it should ... but at the same time a different consist (one of three I had been running) that I had parked in the yard also started moving, mirroring the commands I was sending to the "correct" consist. The offending consist would also respond to its own address, but it continued to mirror commands sent to the other address. (The third consist didn't budge.)

I'm pretty much set on trying the re-set, but it will probably be a couple days before I get a chance. I'll report back. @Maletrain , good advice regarding the Digitrax group ... but I hope it doesn't come to that.

Jim

[Maletrain]

Jim,

I wish you had JMRI set up to look at the DCS50 slots - that would clearly show what is happening.

Without that, my best guess is that the consist that is moving when it is not supposed to be moving was not properly dispatched the last time you used it.

It would help to know in what order you acquired and dispatched the 3 consists with the same throttle and which one moved when it was not supposed to be active.  If you used the command station throttle for anything else (another consist or a single loco) between the time you dispatched that one and when it started moving when you acquired the consist that you intended to move, that would be important for us to know.

You can use op switches to "clear all slots" and even to reset the whole DCS50 system to factory defaults, both of which clear the slots, including breaking all consists.  But, then you need to remake your consists.

So, before doing that, I suggest you try the following:  When you see that sending throttle commands to one consist is moving 2 consists, first, make sure that you PROPERLY dispatch the consist that you do want to move.  Then acquire the one that is moving when it is not supposed to be moving.  Then PROPERLY dispatch that one.  Then reacquire the one you do want to move and see if the other one still moves.  If you have to "steal" one or more of the addresses to do that, let  us know which addresses and in what part of the sequence.

My best guess at what is going on is that the consist that moves when it is not supposed to move was dispatched with a speed step other than zero, or perhaps not dispatched at all.  That would leave it in a slot with the throttle associated with it, even if the throttle is also used to acquire another address.

Sometime the throttles that use pots get bumped off their zero unintentionally, or even get damaged so that they don't always read zero when turned down all the way.  So, this might not be something that resetting the command station software could solve permanently.

Getting a better description of the actual sequence of events that lead to the problem would help figure out why it is happening.

[nstars]

Perhaps something to consider. At the beginning it was mentioned that 5-6 two unit consists were used. With 6 that is more than the 10 slot capacity of the DCS50. However, if these consists are permanent, the easiest solution is ‘Basic’ consisting. The same address for every loco in the consist.

Marc